In Help -> Software Updates -> Manage configuration... there are the plugins, but their status is "The feature is not configured properly.".
Reasons:
No plug-in: "org.eclipse.mtj.pulsar.core" included at runtime.
No plug-in: "org.eclipse.mtj.pulsar.ui" included at runtime.
No plug-in: "org.eclipse.mtj.examples.jadextension" included at runtime.
No plug-in: "org.eclipse.mtj.examples.source" included at runtime.
No plug-in: "org.eclipse.mtj.example.library" included at runtime.
No plug-in: "org.eclipse.mtj.examples.toolkits" included at runtime.
No plug-in: "org.eclipse.mtj.examples.templates" included at runtime.
No plug-in: "org.eclipse.mtj.examples.toolkit.sdkprovidertestclamp" included at runtime.
No plug-in: "org.eclipse.mtj.examples.toolkit.sdkprovidertestclamp2" included at runtime.

I've reinstalled the plugins, and now they are correctly installed without any error in the status.
But there isn't "Java ME" in the Preferences nor in the creation of a new project.
In the workspace there isn't any log. In the configuration the plugins are correctly listed, and the error log is empty.